U.S. Pat. No. 5,875,540, the entire disclosure of which is incorporated by reference herein, discloses a process for forming a stator core in a stator frame. The process involves forming a plurality of core modules or donuts, each of which comprises a plurality of stator core rings laminated together. The stator frame is placed in an upright position. A predefined number of the core modules are then lowered into the upright stator frame. For a power generator which has been in operation for some time and is in need of a new stator core, turning its stator frame upright to receive a new stator core can be very difficult.
U.S. Pat. Nos. 7,302,754; 7,353,586; and 7,395,594, the entire disclosures of which are incorporated by reference herein, are directed at installing stator cores into stator frames without placing the stator frame in an upright position. U.S. Pat. No. 7,202,587, the entire disclosure of which is also incorporated by reference herein, discloses mounting stator core donuts having enlarged grooves in a stator frame using wedges that disperse forces to the donuts in a circumferential manner. The enlarged grooves make installing the donuts less difficult, while the wedges ensure a tight fit of the laminations within the stator frame. U.S. Patent Application Publication No. 2009/0235516, the entire disclosure of which is also incorporated by reference herein, discloses removing a first stator core from a stator frame, servicing frame beams of the stator frame, and installing new keybars into the stator frame such that a second stator core can be inserted into the stator frame. Each of these patents/published applications involves installing stator cores into stator frames that use keybars, otherwise known as building bolts, to directly support the stator core in the stator frame.